Manhole frame and cover



MANHOLE FRAME AND COVER Filed Q t, 18, 1922 Patented Feb. 22, 1927.

UNITED STATES JOHN ROOT, OF CHICAGO, ILLINOIS.

MANHOLE FRAME AIID COVER.

Application filed October 18, 1922. Serial No. 595,313.

This invention relates to manhole frames and covers used principally atstreet or road levels to afford access to'undcrground constructions.

The objects of this invention are ride a construction of manhole frameand cover, with an improved locking and center ing device for the cover,which also renders the construction free fromobjectional rattle whenpassed over by traffic.

The objects of the invention are accomplished by the devices shown inthe accompanying drawing in which- Figure 1 is a plan view of themanholeframe and cover constructed according to this invention.

Figure 2 is a sectional view taken on line 2-2 of Figure 1.

Figure 3 is an enlargeddetail of one of the locking recesses in theinside of the frame.

Figure 4 is a plan view showing one of the recesses.

Figure 5 is an elevation of a portion of the edge of the lid showing oneof the knobs.

The present invention is intended to provide a construction which willresult in the cover becoming wedged in a central position in the frame,and which will be safer than the usual designs of manhole frames andcovers, in that it is not subject to wear by the'cover vibrating in theframe upon the passage of traffic. The wearing of the covers and theirsupporting flanges in some designs, results in a liability of the covertilting in the frame, when the cover is subjected to an eccentric load.

It is also the purpose of the invention to provide a constructionwherein the cover cannot be easily removed from the frame except by theuse of a crow-bar or some other special wedged-shaped tool.-

The construction jillustrated is the circular type of manhole frame andcover, although the invention may be applied to rectangular frames. Thedrawing shows a frame 1, the annular wall 2 of which carries on itsinner surface an annular flange or seat 3 for cover 4.. Above the flange3 on the inner surface of the frame are a plurality of bayonet-slotshaped recesses 5, which extend downwardly from the upper surface of theframe and then transversely at the lower portion. These recesses receivehemispherical knobs 6 on the periphery of the cover. As may be seen fromFigure to pro- 3 and Figure 4, the recesses 5 arewedgeshapedhorizontally, 'i. e., of thcirlower ends '7 than at the enlargedentering end 8 of the recesses with respect to the radius of themanhole; but in the vertical plane the slots o are of the same width,but slope downwardly in the. transverse oxtension. Thus, when the coveris placed in the frame and forced to turn slightlyv in rightshand,direction, the knobs 6 become wedged at the outer ends in the recesses.This causes the cover to properly center in the frame and to becomelocked thereto. When the cover is rotatedinto place, the lugs 6 jam atthe outer ends. The resulting restraining forces therefrom are exercisedhorizontally at right angles to the vertical disturbing forces of thetraffic. The horizontal wedging surfaces are less effective than thevertical wedging surfaces, which alone were depended upon heretofore.When a wheel strikes the cover, the load is suddenly applied downwardlyand then suddenly released. This causes a rebound upwardly which reactsdirectly upon the upper wedging surfaces commonly used, and the force ofrebound is resolved by the angularity of the wedging surface into aforce which tends to unwind or unlock the cover. The covers become looseand the .upperjand lower surfaces of the lugs become battered and worn,so that the cover cannot lock, and even becomes tilted and thrown out ofthe manhole.

'VVhen, as in this invention, the lugs wedge at the outer ends. thesewedging surfaces are not in line with the battering forces of thetraffic and, of course, wear considerably longer than the verticalsurfaces, and also effectually prevent the cover from becoming loosened.7

With this arrangement the cover does not rattle in its frame when passedover by .a vehicle and has no tendency to become released from theframe, but rather to be more firmly wedged therein by thepassage oftrafiic over the cover. The cover is provided with an opening 9 at oneside and within which extends a shoulder 10 on the inner side of theframe. This shoulder serves as an abutment for a tool used in wedgingthe cover into the frame or for releasing it therefrom. The opening 9also serves as a drain for water which collects in the cover.

I claim less depth at said slots being similarly inclined downwardly,peripheral lugs on said cover for engaging in said slots and adapted tojam at the outer ends against the radial Walls of the slots when thecover is rotated intoplace.

2. In a manhole closure, :1 frame having an opening, a cover looselyfitting and seating in saii'l opening having' a plnmlity' of hayonetslots tapering in depth in a horizontal plane, the transverse extensionsof said slots being; similarly inclined downwardly, peripheral knobs onthe said cover {or engaging in said slots and adapted to jam at the endsin the radial. walls of? the slots, said cover having a peripl'ieralrecess, an inwardly projecting lng on said frame, said 111 cooperatingwith said recess to enahle rotating the cover.

8. In a manhole closure, a frame having a recessed opening, a coverloosely fitting in said recess, the side walls of said recess having aplurality of downwardly sloping slots, said slots being tapered inwardlyin the horizontal plane, a plurality of peripheral lugs on said coverfor engaging in said slots, said lugs being adapted to jam at the outerends in said slots.

Signed at Chicago this 10th day of October, 1922. l

JOHN ROOT.

Ill)

